 This separation seems to provide plasticity to the system, as it allows the sensor NLRs to evolve more rapidly in response to the fast evolution of pathogen effectors whereas the helper NLR can evolve much slower to maintain its ability to induce HR.However, it seems that during evolution new helper NLRs also evolved, supposedly, because certain sensor NLRs require specific helper NLRs to function optimally.Bioinformatic analysis of plant NLRs has shown that there is a conserved MADA motif at the N-terminus of helper NLRs but not sensor NLRs.